I can't say that your indicator works. People who code indicators, they don't always follow the same rules. You can see what kind of values the indicator is giving you with "Trace" block. When you know them, you will know how to use them. Depending on the values, you can use some of the blocks in "Conditions for Indicators" category.
"Indicator is visible" works pretty much the same as when you have Indicator > 0 in "Condition"